Nice! If you're handy with some tools, you can find some nice diy tutorials on youtube. Serpadesign has a couple videos where he builds and waterproofs some large enclosures out of woods, but his designs would probably require a little adjustment as they only held about 6-8 inches of water because he used them for paludariums. Overall the big one was the size of a 180 gallon tank though.
From the sound of it, yours is going to be a full aquarium?
It can be. The plants that are in it can be emerged and submerged so whatever strikes me at the moment. Sometimes it’s pretty full, sometimes half, sometimes only a few inches of water. I like the flexibility.